Research On Material Metabolism Of Urban Infrastructure And Urban Mining

At present,China is still in the period of accelerated development of industrialization and urbanization,the demand for mineral resources is great,and the limited nature of resources has increasingly become a key factor constraining the sustainable development of the economy.Studying the material metabolism of urban infrastructure and its resource and environmental impacts,analyzing the spatial and temporal evolution of urban minerals are crucial to achieving sustainable economic development,accelerating the reform of the ecological civilization system,and building beautiful China.The study was conducted in Shanghai,a representative city of China's rapid urbanization,using Material Flow Analysis(MFA)Research Methods Based on Geographic Information System(GIS)Model Database,to study the spatial and temporal evolution of material inflows,material stocks,and material outflows in major urban infrastructures in Shanghai from 1930 to 2015,also analyzes the effects of its resources and environment,and finally analyzes the spatial-temporal evolution characteristics of the distribution of urban mineral hot spots in Shanghai,providing a reference for urban construction and recycling of secondary resources,at the same time,it also provides a reference for researchers to carry out such studies in other cities.This thesis has reached the following conclusions through research:(1)In the past 85 years,the material stock of the four types of major infrastructures in Shanghai has steadily increased,and the total material stock increased from 12.29 million tons of the three types of infrastructures,residences,roads,and railways in 1930 to 688.72 million tons of four types of infrastructures in 2015,an increase of 55 times,with an annual growth rate of 5%.Among them,residential buildings accounted for the largest proportion,accounting for an average of more than 97% over the years,the proportion of transportation infrastructure is relatively small,followed by roads,railways,and subways in descending order.The material with the highest proportion of the four types of infrastructure materials in Shanghai is gravel,which has been over 50% over the years,followed by cement and bricks,and steel,lime,wood and glass accounted for relatively low proportions.From 1930 to 2015,Shanghai's infrastructure material stock showed a trend of continuous development in the suburbs and above the space,over 70% of material stocks have been accumulated in urban centers and near suburbs,residential buildings have high material stock density but uneven distribution,transportation facilities are widely distributed and the material stock density is controlled within a certain range.(2)From 1930 to 2015,although the total material inflow of infrastructure in Shanghai was fluctuating,it showed an overall upward trend,the total consumption of materials increased from 11.59 million tons in 1930 to 43.41 million tons in 2015,an increase of 2.7 times,of which residential buildings accounted for the largest proportion,accounting for more than 95% over the years,followed by road,railway,subway.The largest proportion of the four types of infrastructure inflow is gravel,and the proportion of inputs in various material categories for various infrastructure facilities is basically stable.The inflow of infrastructure building materials presents a pattern similar to urban land expansion in space.The general trend of consumption of natural resources by infrastructures in Shanghai from 1930 to 2015 is consistent with the total material inflow over the years,although there were fluctuations,the overall trend is still rising,the consumption of iron ore increased from 50,000 tons in 1930 to nearly 3 million tons in 2015,an increase of 53 times.Limestone consumption caused by infrastructure construction increased from 1 million tons in 1930 to 6 million tons in 2015.In general,infrastructure construction increasingly depends on iron ore,and the proportion of limestone consumption has declined.(3)In terms of the spatial and temporal evolution of infrastructure construction waste and carbon emissions,total infrastructure outflow has generally increased in the past 85 years,increasing from 0.19 million tons in 1930 to 25.06 million tons in 2015,it has grown 130 times,with an average annual growth rate of up to 150%,the main construction waste is gravel,brick and cement.The proportion of waste generated by infrastructure is almost the same as the inflow of material,and the material outflow of the road exceeded the residential buildings in 2010.The spatial distribution of waste generated by transportation facilities and residential buildings is increasing,and more than half of the material outflow comes from the urban center area,this is mainly because this area is the main storage area for material stocks,similar to the spatial distribution of material stocks,the growth rates of construction wastes are the fastest in the suburbs.Due to the continuous accumulation of infrastructure material stock,the implied carbon emission also showed a fluctuating upward trend,which almost same with the trend of the total material stock of infrastructures,increased by more than 72 times from 2.1 million tons in 1930 to 155 million tons in 2015.(4)From the perspective of the spatial-temporal evolution of urban minerals in Shanghai,from 1930 to 1950,the distribution of urban mineral hot spots gradually narrowed,the hot spots are mainly distributed within 10 km and 20 km from the center of the city.After 1960,the distribution of hot spots began to gradually expand,from 1990,the distribution of point-like hot spots in the suburbs and counties was even more obvious,and hot spots increased within 30 km to 40 km from the city center.2010 is the period with the widest distribution of urban minerals in Shanghai.In 2015,Shanghai's urban minerals are mainly concentrated in the urban center area and Jiading,central Songjiang,northern Minhang,and the Huangpu River area in the Pudong New Area.Through the hotspot analysis of urban minerals in Shanghai from 1930 to 2015,and analyzing the characteristics of their spatial and temporal evolution,it was found that the main distribution area of urban minerals in Shanghai is still the urban center area,The overall layout shows that the farther away from the city center,the smaller the geographical distribution of hot spots,and it shows a tendency to shift to the surrounding suburbs and counties.Therefore,the areas that generate a large amount of construction waste should be the focus of attention for urban construction and secondary resources development.